The present invention is related to Japanese patent application No. 2000-68665, filed Mar. 8, 2000; 2001-11932, filed Jan. 19, 2001 the contents of which are incorporated herein by reference.
The present invention relates to a hydrogen storage unit, and more particularly, to a hydrogen storage unit for charging and discharging hydrogen gas.
Conventionally, hydrogen storage units provided with hydrogen absorption material for absorbing hydrogen gas (such as a hydrogen absorption alloy), have been proposed. Such a hydrogen storage unit is proposed in JP-A-62-246699. Here, a conventional hydrogen storage unit is provided with a hydrogen absorption alloy within a hydrogen storage container and a filter portion having an adsorbent within the hydrogen storage container. If the hydrogen absorption alloy is poisoned by impurities such as moisture and air, the hydrogen absorption capacity is degraded. Therefore, the poisoning materials described above are selectively adsorbed by the adsorbent in order to prevent the hydrogen adsorption capacity from being degraded.
In the conventional hydrogen storage unit, when hydrogen gas supplied from hydrogen supply equipment is absorbed in the hydrogen absorption alloy, the hydrogen gas passes through the filter portion, and the poisoning materials described above are adsorbed therein. Further, when hydrogen gas is discharged to hydrogen consumption equipment set outside the storage tank, the hydrogen gas again passes through the filter portion. Then, the filter portion adsorbent degrades due adsorption of the above-described poisoning materials, thereby losing the hydrogen adsorption capacity. Therefore, the filter portion adsorbent is moved outside the hydrogen storage unit and is heated to recover hydrogen adsorption capacity.
In the conventional hydrogen storage unit, the filter portion adsorbent must be moved to a different place in order to recover the filter portion adsorbent, thereby making recovery troublesome.
In view of these and other drawbacks, a hydrogen storage unit according to the present invention, comprises a hydrogen storage container containing a hydrogen absorption material, a filter portion and a heat supply means. Here, the filter portion includes an adsorbent for adsorbing impurities contained in hydrogen gas stored in the hydrogen storage unit. Further, the heat supply means, provided in the filter portion, includes heating means for heating the filter portion to enhance elimination of impurities adsorbed in the adsorbent.
Therefore, the elimination of the impurities from the adsorbent is enhanced by heating the filter portion with the heat supply means, and the adsorbent can be recovered.
Since adsorption capacity of the adsorbent is increased as temperature decreases, the heat supply means according to another aspect includes a cooling means for cooling the filter portion adsorbent to enhance the adsorption of impurities in the filter portion.
In another aspect, the heating means is controlled based on purity of hydrogen gas discharged. When impurities are not contained in the hydrogen gas, it can be determined that the elimination of impurities from the filter portion is completed. Accordingly, if it is determined whether or not the heating means stops heating the filter portion based on the purity of discharged hydrogen gas, the filter portion can be prevented from being heated more than required by the heating means.
In another aspect, the heating means is controlled based on the hydrogen gas charge. For example, the time expended for charging hydrogen gas into the hydrogen storage container can be used as information relating to the hydrogen gas discharge. That is, as charging time of hydrogen gas becomes longer, the amount of impurities adsorbed in the filter portion becomes larger. As the amount of impurities adsorbed in the filter portion becomes larger, the time required for heating the filter to eliminate the impurities from the filter portion becomes longer. On the contrary, as hydrogen gas charging time becomes shorter, the time required to heat the filter portion becomes shorter.
Furthermore, for example, the amount of charged hydrogen gas can be used as information relating to the hydrogen gas charge. In this case, as the amount of charged hydrogen gas becomes larger, the amount of impurities adsorbed in the filter portion becomes larger, and the heating time of the heating means must be longer. When the amount of charged hydrogen gas is small, the heating time shortened.
In another aspect, the heating means is controlled based on information relating to hydrogen gas consumption. For example, the amount of hydrogen gas discharged into the hydrogen consumption equipment can be used as the information relating to hydrogen gas consumption. That is, as the amount of hydrogen gas passing through the filter portion becomes larger, impurities are eliminated from the filter portion more rapidly, and the heating time of the filter portion by the heating means can be shortened. On the contrary, when the amount of hydrogen gas passing through the filter portion is small, impurities are eliminated from the filter portion slowly, so that the heating time of the filter portion by the heating means must be longer.
The above-described filter portion can be provided outside the hydrogen storage container or inside. If inside, both of the hydrogen storage container and the filter portion can be heated and cooled by one heating means and one cooling means.
In another aspect, the filter portion and the hydrogen storage container are disposed so that hydrogen gas flows through the filter portion in a hydrogen storage mode (where hydrogen gas is stored in the hydrogen storage container) and a hydrogen discharge mode (where hydrogen gas is discharged outside the hydrogen storage container).
The impurities generated by recovering the filter portion are discharged outside the hydrogen storage container together with hydrogen gas discharged outside in the above-described hydrogen discharge mode. Therefore, the impurities generated during recovery cannot be adsorbed in the hydrogen absorption material within the hydrogen storage container, thereby not poisoning the hydrogen absorption material.
Another aspect includes a first supply portion connected to a hydrogen supply equipment, a second supply portion connected to a hydrogen consumption equipment, a third supply portion connected to the hydrogen storage container, and a supply line including a switching portion. Here, the switching portion switches connections between the first supply portion and the third supply portion and connection conditions between the second supply portion and the third supply portion.
Accordingly, in the hydrogen storage mode, connection is performed between the first supply portion and the third supply portion, and connection is interrupted between the second supply portion and the third supply portion, thereby supplying hydrogen gas inside the hydrogen storage container from the hydrogen supply equipment through the filter portion. On the contrary, in the hydrogen discharge mode, connection is interrupted between the first supply portion and the third supply portion, and connection is performed between the second supply portion and the third supply portion, thereby supplying hydrogen gas into the hydrogen consumption equipment from the hydrogen storage container through the filter portion.
In another aspect, the hydrogen storage container has one closed end and another end having a hydrogen supply port, and the filter portion can be disposed at the hydrogen supply port to make hydrogen gas pass through the filter portion in both the hydrogen storage mode and the hydrogen discharge mode. Further, the hydrogen storage container can be bottle shaped, where one end is closed and the other end has a hydrogen supply support, so that the hydrogen storage container has another advantage of not requiring a specific structure as the hydrogen storage container.
In another aspect, the hydrogen storage container and the filter portion may be separated from each other, a valve may be provided therebetween set to open during hydrogen gas charging and discharging. Thereby, when the filter portion must be replaced due to failure, impurity gases are prevented from entering the hydrogen storage container by closing the valve during replacement.
In another aspect, the heating and cooling sequences of the hydrogen storage container and the filter portion may be changed between hydrogen gas charging time in the hydrogen storage container and the time of discharging hydrogen gas from the hydrogen gas container. Impurities must be eliminated from hydrogen gas during initial charging. At this time, since the filter portion is first cooled, impurities can be more effectively eliminated from hydrogen gas by the filter portion. Since the hydrogen storage container is first heated during discharging, the impurities from the filter portion are not preferentially discharged, thereby preventing excessive purity degradation of discharged hydrogen gas.
In another aspect, impurities can be more effectively eliminated from hydrogen gas during hydrogen-gas charging, and the purity of discharged hydrogen gas can be prevented from excessively degrading during hydrogen-gas discharging.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.